It can be difficult for a person using a spray gun to keep the spray nozzle at the optimum distance and orientation from the surface being painted or coated, while at the same time applying the proper thickness of finish to the surface. This is especially difficult for novices. As an example of the difficulties facing novices, consider that merely placing the nozzle too close to the surface can cause an uneven wet film build as well as runs. The quality and uniformity of coverage typically improves as the distance between the spray nozzle and the surface increases, however, it is not desirable that the spray distance between the nozzle and the surface be substantially larger than an optimum spray distance. Letting the spray distance be too large can cause overspray, paint fogging, or otherwise decrease the efficiency of paint or coating transfer onto the surface. Having the nozzle too far from the surface not only increases the number of coats necessary to provide a sufficient wet film build for proper paint coverage, but also increases the cost of complying with environmental regulations. High levels of overspray and fogging increases the amount of volatile organic compounds that can escape from the spray booth, and also increases the amount of hazardous waste that must be disposed of from spray booth air filtering systems.
Training and practical experience help novices improve their skills. Hands on training has been very successful in improving coating efficiency and reducing environmental impacts. However, hands-on training is time consuming, labor intensive and expensive. These factors have made training of large groups, such as military personnel, complicated. In addition, hands-on training of finishing techniques with the actual finishing equipment and materials has other drawbacks including the generation of harmful emissions, waste of finishing material, and limited ability to measurement performance criteria such as transfer efficiency or build efficiency. As a practical matter, hands-on training tends to limit the number of techniques that can be practiced and evaluated, especially with respect to multiple finishing materials and surfaces.
The use of computer simulations and virtual reality systems to foster practice and training of proper spray painting techniques is known in the prior art. For example, the application of liquid coatings in industrial paint booths has been simulated by the Johnson Center for Virtual Reality located at Pine Technical College in Minnesota. This system uses an electromagnetic six degree of freedom tracking system to track the position and orientation of a spray gun controller with respect to a projection screen. Computer models are used to display a virtual spray pattern on the screen in accordance with signals from the tracking system. The goal of this virtual reality system is to provide the user with a realistic training environment to learn proper spray techniques. Another system from Pine Technical College uses a head-mounted display unit instead of a display screen. A virtual three-dimensional spray painting environment is displayed to the user wearing the head-mounted display unit such that the user perceives him or herself being immersed within the virtual environment.
Because application of the liquid coating is simulated, no material is expended and a harmful emissions and waste are not produced. Also, user performance data can be stored in a database for print out and later monitoring. To the extent that computer simulation and virtual reality systems provide a realistic experience, these systems can be a worthy supplement to hands-on training.
One object of the present invention is to develop a virtual coating application system that provides a more realistic simulation of the spray painting experience for the user. The invention as described herein provides several features contributing to improvements in this respect. Another object of the invention is to provide a virtual coating application system that is able to monitor performance data such as total finishing time, transfer efficiency, build efficiency, amount of finish used and approximate mil thickness and provide the user and the instructor with meaningful feedback, which in some cases can be immediate.